The present invention relates to a release coating composition and a release sheet. The release coating composition of present invention is used, for example, in the fields described in COATINGS, V, pp. 427-442, SKEIST INCORPORATED WHIPPANY, N.J. 07981 U.S.A., MAY 1992, and used for a pressure sensitive adhesive tape, a pressure sensitive adhesive sheet or the like, of which base material is mainly paper or a plastic film.
Generally, in a pressure sensitive adhesive matter such as a pressure sensitive adhesive tape, a pressure sensitive adhesive shoot and the like which are made by coating a pressure sensitive adhesive on one face or both faces of a sheet type base material (or a sheet type carrier), a release sheet such as release paper and the like is adhered to a pressure sensitive adhesive-coated face (an adhesive face) of the matter in order to protect this face. In case where a pressure sensitive adhesive matter takes the form of a shoot, a tape or the like, the matter is preserved in a wound roll form. In this wound form, a pressure sensitive adhesive-coated fact of the matter which is wound outside is adhered to a backing of the base material (here, the backing of the base material is a face reverse to a pressure sensitive adhesive-coated face of the base material) of the matter which has been wound inside. A release coating composition is coated, to improve releasing performance in use, on the surface of the release sheet (here, the surface of the release sheet is a face to which the pressure sensitive adhesive-coated face of pressure sensitive adhesive matter is adhered), or on the backing of the base material of pressure sensitive adhesive matter which is wound in the roll form.
Hitherto, as a release coating composition, a silicone type and a long chain alkyl type have been industrially produced, and they are used for a pressure sensitive adhesive tape, a pressure sensitive adhesive sheet and the like. In case of using the silicone type release coating composition, because it has usually been cross linked by using a condensation reaction or an additive reaction, it is superior in heat resistance, solvent resistance and water resistance and has high releasing performance because of its low surface activity. However, the silicone type release coating composition has problems in residual tackiness and writing performance (in the specification, writing performance means that writing with water-born ink is possible on the face coated with a release coating composition.) and also, has problems of deteriorating the adhesive strength of a pressure sensitive adhesive tape, a pressure sensitive adhesive sheet and the like because of release coat transfer to an adhesive layer. Therefore, recently, the long chain alkyl type release coating composition has been noticed, which is superior in residual tackiness and writing performance and has releasing performance of medium grade. Practically, for the long chain alkyl type release coating composition there are a polyvinyl alcohol-octadecyl isocyanate adduct (refer to Japanese Official Patent Gazette No. showa 29-7333), a polyethyleneimine-octadecyl isocyanate adduct (refer to Japanese Official Patent Gazette No. showa 40-17661) and the like, and these compounds are in general diluted by a solvent and then coated, however, recently, it has also been attempted that a water dispersion (Japanese Official Patent Provisional Publication Nos. heisei 3-50279 and 3-86776) of the long chain alkyl type release coating composition is diluted by water and then coated.
However, the above-mentioned conventional long chain alkyl type release coating composition has problems that its heat resistance is inferior and it deteriorates the adhesive strength of a pressure sensitive adhesive tape, a pressure sensitive adhesive sheet and the like because of release coat transfer to an adhesive layer.